1. Field of the Invention
The present invention relates to a pressure damper for damping unnecessary vibrations in liquid, and a liquid jet head including the pressure damper.
2. Description of the Related Art
In these days, there are provided many ink jet type recording apparatuses which perform recording of an image or a character by discharging ink droplets on a recording medium such as a recording sheet. In a recording apparatus of this type, ink is supplied from an ink tank or an ink cartridge to a liquid jet head, which is mounted on a carriage, via an ink supply tube. Ink droplets are discharged on the recording medium from nozzles of the liquid jet head while the carriage is caused to move in a main scan direction. At the same time, the recording medium is caused to move in a sub scan direction. In this manner, the recording is performed on the recording medium.
In this case, by the movement of the carriage, the ink supply tube pulsates and ink inside the ink supply tube moves, and thus pressure fluctuation is generated. This pressure fluctuation is applied to the liquid jet head through the ink supply tube. As a result, change in discharge droplet amount (drop volume) of the ink occurs, and hence quality of the image and the character recorded on the recording medium is deteriorated.
Therefore, in order to alleviate unnecessary pressure fluctuation applied to the liquid jet head, there is proposed a technology of alleviating the pressure fluctuation by providing a pressure damper in the middle of the ink supply tube. The pressure damper has a cavity in which ink is storable to some extent, and the pressure fluctuation of the ink is alleviated by causing the ink flowing out from the ink supply tube to flow into the cavity (for example, see JP 05-201015 A).
However, when the unnecessary pressure fluctuation applied to the liquid jet head is large, the capacity of the pressure damper is also required to be large. In particular, in a case of a large-sized liquid jet apparatus, a long ink supply tube is provided, and hence larger pulsation occurs in the ink supply tube when the carriage moves. Further, in order to obtain an effect similar to that provided by the pressure damper, it is conceivable to provide a sub-tank between the liquid jet head and an ink storing tank or an ink cartridge. However, in this case, there is a problem in that the liquid jet apparatus becomes large in size.